Antistatic treatment and apparatus



March 1967 H.,W. SMITH ETALY 3,308,343

ANTISTATIG TREATMENT AND APPARATUS Filed Nov. 12, 1964 2 Sheets-Sheet 1March 7, 1967 w. SMITH ETAL ,3 8,

" I ANTISTATIC TREATMENT AND APPARATUS Filed NOV. 12, 1964 2Sheets-Sheet 2 AS PRESSURE REG UL ATOR e MMMOISTURE TEMPERATURE CONTROLI 68 70 L58 N 7 66 if 7? 35 7 FMZ as 63 LSQQAL A 75 164 5g 7/ fitJAIME/V7025. 0/9040 W SM/fl/ 650265 A7. Kale/ 05 United States PatentOfifice 3,308,343 Patented Mar. 7, 1967 3,308,343 ANTISTATIC TREATMENTAND APPARATUS Harold W. Smith, San Marine, and George A. Korkos, LosAngeles, Caliii, assignors to Euler-Jet Corporation, Phoenix, Ari'z., acorporation of California Filed Nov. 12, 1964, Scr. No. 410,651 11Claims. (61. 3172) This invention relates generally to antistatictreatment of electrically charged objects, and more particularlyconcerns ion generation and dispensing apparatus for altering the staticcharge on work surfaces.

In certain processing operations there has long been a need for removingstatic charge from work surfaces. Typical processing apparatus wherestatic charge builds up on fiber or paper surfaces includes thefollowing: feeder aprons in cotton gin stands, cotton gin lint cleaners,slides and overhead feed distributors, rollers in cotton roller gins,textile mill card webs, sliver and tow, and looms for processing eithernatural or synthetic fibers, paper handling equipment such as printingpresses, and rug fiber manufacturing, process, handling-and transportingequipment and hair treating apparatus. Such charge build-up oftenresults in balling, sticking and jamming of the fiber, paper or hairbeing processed, inhibiting the efiiciency of the processing operation.Past efforts to solve this problem have not proved to be entirelysatisfactory, and do not offer the unusual features and advantages ofthe present invention, insofar as we are aware.

It is a major object of the present invention to overcome the chargebuild-up problems discussed above through the provision of unusuallysimple, compact and highly effective ion generation and dispensingapparatus for altering, as for example neutralizing, the static chargeon work surfaces. Basically, the apparatus comprises a chamber having agas inlet and a sonic orifice outlet, means presenting a pointed tipupstream of the orifice outlet and to supply sufficiently high voltageto effect production of ions in a corona at the tip, and means to supplya stream of pressurized gas to flow into the chamher and adjacent thetip to carry the bulk of the ions through the orifice, the latter beingangled to jet the gas stream and ions in a wide angle discharge pattern.It is another abject to achieve the wide angle ion discharge pattern ina highly effective and simple manner, in order that decay of ionconcentration may be kept low while a large area of work may be treated.This objective is realized by providing a metallic front orifice platehaving a rear recess into which the pointed tip projects in order thatthe corona may be swept by high velocity gas, the plate discharge orficecommunicating with that recess and being formed as a narrow slot theopposite end walls of which diverge at a wide angle.

It is a still further object of the invention to provide a simple andefiicient high voltage power supply for the pointed tip, the lattertypically being formed by a needle. As will appear, the power supplybasically comprises a circuit including a transformer to supplyalternating current above 2,000 volts at the transformer secondary coil,and simple means electrically connected in series between the coil andsaid needle to effect su ply of positive or negative ions at the needlecorona. Typically, the circuit includes first and second branchesrespectively electrically connected between spaced taps of thetransformer secondary coil and the needle, a first rectifier connectedin one branch to pass current away from the needle and a secondrectifier connected in the other branch to pass current toward theneedle. As a result, either positive or negative ions may be produced atthe needle corona for distribution to the work. Further, each branchincludes a pair of terminals located to removably engage a fuse to passcurrent between the terminals, so that the fuse may be selectivelypositioned to alternately electrically interconnect the needle with thepositive or negative high voltage supply.

Further objects include the provision of simple and effective means tocontrol the quantity of ions supplied to the work by controlling thepressure, temperature and moisture content of the gas which is suppliedto the work via the ion producing corona, and the effective adaptationof the ion generating and dispensing apparatus to processing equipmentsuch as a cotton gin.

These and other objects and advantages of the invention, as well as thedetails of illustrative embodiments, will be more fully understood fromthe following detailed description of the drawings, in which:

FIG. 1 is an overall perspective view showing the combination of the iongenerating and dispensing apparatus with a cotton gin;

FIG. 2 is an enlarged perspective view of the apparatus cabinet andcontrols;

FIG. 3 is a vertical cross section taken through the ion generating anddispensing apparatus;

FIG. 4 is a power supply circuit diagram;

FIG. 5 is an enlarged fragmentary section taken on line 55 of FIG. 3;and

FIG. 6 is a view taken on line 66 of FIG. 3.

Referring first to FIG. 1, a cotton gin is indicated generally at 10 ashaving a cotton feed 11, a slide 12 along which cotton fiber 13descends, and a lower unit 14 containing saws or other apparatus toclean and process the cotton. Cotton fiber 13 tends to develop staticcharge and to ball up on the slide 12, preventing uniform delivery anddistribution thereof to the lower unit 14, so that the latter functionsless efficiently than is possible in the absence of the static chargebuild-up on the cotton. To solve this problem, the ion generating anddispensing apparatus shown at 15 is centrally mounted as by bail supportbracket 16 directly facing the slide 12 so as to jet a highconcentration of ions, as in an ionized gas stream, in a forwarddirection and over a wide angle discharge pattern 17 for continuouslytreating the cotton descending on the slide. Such treatment alters thestatic charge build-up on the cotton fibers, as for example byneutralizing the static charge, to stop balling, bunching or non-uniformdelivery of the cotton to the lower unit. As a result a cleaner, morehigh grade cotton product is produced by the gin, enhancing its economicvalue.

Extending the description to FIGS. 2 and 3, the apparatus 15 isillustrated to comprise a cabinet 18 having a front plate 19 mountingthe electrical power supply line at 20, a line fuse holder 21, a neonpilot or indicator bulb 22, an on-off switch 23, an active fuse holder24, a dummy fuse holder 25, and an air or gas supply line 26.

Apparatus 15 also includes a dielectric, as for example plastic, chamber27 contained within the cabinet 18 and having a gas inlet 28 to whichline 26 delivers. The

chamber 27 includes a metallic front plate 29 forming a sonic orificeoutlet 30 at the front side of the plate. In accordance with animportant aspect of the invention, the orifice is angled to jet the gasstream and ions forwardly in a wide angle discharge pattern as indicatedat 31 in FIG. 5, the discharge pattern having reduced thickness asbetter seen in FIG. 3. This result is achieved by providing an orificethe outlet side of which has the form of a narrow width slot 32 boundedat opposite ends by plate walls 33 which diverge forwardly at a wideangle, typically obtuse. As a result, the ion discharge patternencompasses the width of the slide 12 in FIG. 1, with ion deliveryconcentrated in a relatively thin zone across the span of the side andthrough which the cotton fibers descend successively, thereby realizingmost effective anti-static treatment since ion decay is compensated forby higher ion concentration in a given unit area at the slide.

Referring back to FIGS. 3 and 4, the invention also includes first meanspresenting a pointed tip upstream of the sonic orifices outlet and tosupply sufficient high voltage to effect production of ions in a coronaat the tip. Typically, the first means comprises a needle 35 forming thepointed tip 36 in the chamber 27 and which projects into a recess 37formed in the rear side of the plate 29 to communicate with orifice 30.In this regard the high voltage supplied to the tip serves to effectproduction of a corona in the recess 37 since the plate 29 iselectrically conductive and is grounded to the cabinet 18 as by mountingfasteners 38. The voltage at the tip must be in excess of 2,000 volts,and typically lies between 4,000 and 6,000 volts. Also, the air or gasdelivered into the chamber 27 via line 26 is pressurized to between 20and 45 p.s.i. The size of the orifice 30 is about to 4 inch, and the tip36 is closely spaced to the orifice to produce the high ionconcentration desired, a typical spacing being between 1.4 to 3.2millimeters. The needle is mounted to a holder indicated at 40 and whichhas threaded adjustable connection at 41 to the chamber to vary the gapbetween the tip 36 and orifice 30. A dielectric cross piece 42 in thechamber acts to center the needle and tip 36 with respect to recess 37.Typically, air is delivered via line 26 to the chamber 27 at flow ratesof around 350 c.f.m. Ion concentration of about to 10 ions per cubiccentimeter of positive or negative polarity leaving the orifice can beproduced in this manner.

Referring to FIG. 4, the components of the simple and highly effectivepower supply circuit shown are typically contained within cabinet 18.The circuit includes a transformer 50 having a primary coil 51 with theinput leads 52 and 53 across which the neon bulb 22 is connected. Lead52 has switch 23 and a variac type resistance control 55 connected inseries therewith, while the other lead has a fuse 56 connected in serieswith it. Fuse 56 is normally held by the removable holder 21 seen inFIG. 1. The primary typically connects via plug 64 with an AC. 115 volt,60 cycle source.

The secondary coil 57 of the transformer has branches 58 and 59connected to its opposite end taps 60 and 61. A rectifier 62 isconnected into branch 58 to conduct current away from the needle 35,thereby to place a positive voltage on the tip 36, whereas a rectifier63 is connected into branch 59 to conduct current toward the needle 35,thereby to place a negative voltage on the tip 36. For example, thesecondary coil may deliver 4,000 volts R.M.S. to two high voltagecartridge type selenium rectifiers 62 and 63, rectification taking placewith conversion to about 5,000 volts D.C. filtered by two 500 p.,ufd. 10kv. condensers 66 and 67. The latter are connected between ground andpoints 68 and 69 in the branches 58 and 59 respectively. Currentlimiting safety resistors 70 and 71, typically of 50 megohm 2 wattrating, are also connected in the respective branches 58 and 59.

Another feature of the invention is the provision for simple, direct andrapid selection of positive or negative ion production at the needletip, without arcing. In this regard, the circuit includes acartridge-type fuse 72, and each branch 58 and 59 includes a pair ofspaced terminals positioned to removably engage the fuse ends to passcurrent between the terminals. Fuse 72 is carried by plug-in holder 24in FIG. 2 for quick interchange with dummy holder 25. Fuse receivingterminals in branch 58 are indicated at 74 in FIG. 4, while terminals 75are in branch 59.

Finally, means to control the pressure of gas and air delivered to thechamber 27 may take the form of a pressure regulator 81 downstream of apump 76 in FIG. 3, the concentration of ions in the jetted pattern 31vbeing changed by adjusting the regulator 81 at 82. Another way tocontrol the ion concentration is to control the speed of the pump drive77 at 78. Means to control the moisture content and temperature of thegas delivered to the pump is indicated at 79 and 80, these factors alsoaffecting the ion concentration in the discharge 31. The

variac 55 may also be adjusted to vary the input voltage and hence thevoltage at the tip 36 for controlling the ion concentration. In thisregard, the plate 29 need not be grounded to produce the corona, and itmay comprise an insulator.

The apparatus 15 described above may be used for many different staticcharge altering purposes, as for example are listed in the introduction.

We claim: p I I 1. Ion generation and dispensing apparatus for alter ngthe static charge of work comprising a chamber having a gas inlet and asonic orifice outletat the chamber front, the orifice minimum crossdimensions having less than A inch first means presenting a pointed tipin the Gharfi= ber upstream of and toward the orifice outlet in closeproximity thereto and to supply sufiic-iently high voltage to effectproduction of ions in a corona at the tip, and second means to supply astream of pressurized gas to flow into said chamber and adjacent saidtip to carry the bulk of the ions at high velocity through the orifice,said orifice being angled to jet the gas stream and ions forwardly in awide angle discharge pattern.

2. Apparatus as defined in claim 1 in which said chamber includes ametallic front plate having a recess at the rear side thereof into whichsaid tip projects, the plate forming said orifice outlet whichcommunicates with said 7 recess, the orifice having the form of a slotbounded at opposite ends by plate walls which diverge forwardly at awide angle. I a

3. Apparatus as defined in claim 1 in which said first means comprises aneedle forming said tip and a circuit including a transformer to supplyalternating current above 2,000 volts at the transformer secondary coil,and rectifier means electrically connected in series between said see=ondary coil and said needle.

4. Apparatus as defined in claim 3 in which said circuit includes firstand second branches respectively electrically connected between spacedtaps of the transformer secondary coil and said needle, said rectifiermeans including a first rectifier connected in one branch to passcurrent flowing away from the needle and a second rectifier connected inthe other branch to pass current flowing toward the needle.

5. Apparatus as defined in claim 4 in which the circuit includes a fuse,and each branch includes a pair of spaced terminals positioned toremovably engage said fuse to pass current between the terminals,whereby the fuse may be positioned to alternately electricallyinterconnect the pair of terminals of one or the other branch in orderto effect selective production of positive or negative ions at theneedle tip.

6. Apparatus as defined in claim 5 including a cabinet containing saidcircuit and having a control plate contain ing first and second openingsproximate each of which a pair of said terminals is located so that thefuse may be manipulated between said pairs of openings from a positionat the cabinet exterior.

7. Apparatus as defined in claim 4 in which each branch includes acurrent limiting resistor, and the circuit includes a first filtercapacitor connected between ground and a point in the first branch inseries between said first rectifier and the needle, and a second filtercapacitor connected between ground and a point in the second branch inseries between said second rectifier and the needle.

8. Apparatus as defined in claim 1 including means to control thepressure of the gas flowing to said chamber.

9. Apparatus as defined in claim 1 including means to control the rateof flow of gas to said chamber.

10. Apparatus as definedin claim 1 including means to control thetemperature and moisture content of the gas flowing to said chamber.

11. Apparatus as defined in claim 1 including a cotton gin forming azone through which cotton travels and tends to develop a static charge,and means to support said apparatus with said orifice directed towardsaid zone and sufiiciently proximate thereto to inject ions into thecotton for reducing the static charge thereon.

References Cited by the Examiner UNITED STATES PATENTS 6/1936 Yaglou317-4 7/1965 Rosenthal 25049.5

OTHER REFERENCES Static Electricity, Francis B. Silsbee, Circular of theNational Bureauof Standards C438, issued June 10, 1942, pages 13, 20-21.

1. ION GENERATION AND DISPENSING APPARATUS FOR ALTERING THE STATICCHARGE OF WORK COMPRISING A CHAMBER HAVING A GAS INLET AND A SONICORIFICE OUTLET AT THE CHAMBER FRONT, THE ORIFICE MINIMUM CROSSDIMENSIONS HAVING LESS THAN 1/4 INCH FIRST MEANS PRESENTING A POINTEDTIP IN THE CHAMBER UPSTREAM OF AND TOWARD THE ORIFICE OUTLET IN CLOSEPROXIMITY THERETO AND TO SUPPLY SUFFICIENTLY HIGH VOLTAGE TO EFFECTPRODUCTION OF IONS IN A CORONA AT THE TIP, AND SECOND MEANS TO SUPPLY ASTREAM OF PRESSURIZED GAS TO FLOW INTO SAID CHAMBER AND ADJACENT SAIDTIP TO CARRY THE BULK OF THE IONS AT HIGH VELOCITY THROUGH THE ORIFICE,SAID ORIFICE BEING ANGLED TO JET THE GAS STREAM AND IONS FORWARDLY IN AWIDE ANGLE DISCHARGE PATTERN.